which ukulele should I get?

I've been Playing the cello for about four years now and decided to
take on a new challenge, learn how to play the ukulele. The two
ukuleles i've narrowed down to are the Lanikai LU-21 and the Kala
Ka-s, But any other suggestions would be great too. my question is
which one should I get? My local guitar center has the Lanikai LU-21
in soprano and concert size, so should I go with the LU-21 because i
could try it out? or take the risk and by a different one online.
Also, I am stuck between the concert or soprano ukulele. If i've
played cello then would a bigger or smaller ukulele benefit me?
THanks!